How did the SS respond to changing the list of prisoners who would board transport that would transfer prisoners to another camp or would send them to the gas chambers?

The SS did not care which prisoners boarded a train. Frankl explains, "A definite number of prisoners had to go with each transport. It did not really matter which, since each of them was nothing but a number." The prisoners were sometimes able to switch numbers with another, who would take his place in the transport.